Flatten numpy array but also keep index of value positions?

Question

I have several 2D numpy arrays (matrix) and for each one I would like to convert it to vector containing the values of the array and a vector containing each row/column index.

Answer 1

You can try this using itertools

import itertools
import numpy as np
import pandas as pd

def convert2dataframe(array):
    a, b = array.shape
    x, y = zip(*list(itertools.product(range(a), range(b))))
    df = pd.DataFrame(data={'V':array.ravel(), 'x':x, 'y':y})
    return df

This works for arrays of any shape, not necessarily square matrices.